Abstract: Stress-skin panels can be manufactured by locating the skins of such panels against mold surfaces which are spaced from one another so that spacers separate these mold surfaces along their side edges. A composition capable of setting up so as to form a rigid, porous foam which is bonded to the skins is introduced into the space between the mold surfaces and the spacers through the use of a movable nozzle structure which introduces substantially equal quantities of the composition along a line extending between the spacers. The nozzle structure is moved in the space between the mold surfaces from one end of the space to the other in such a manner that uniform amounts of the composition are placed within the space along the length of the space. When the composition has become rigid the apparatus is disassembled and the panel produced is removed from it.